1 files changed, 10 insertions, 2 deletions

diff --git a/mergepdf b/mergepdf
index deb8e89..5de7e19 100755
--- a/mergepdf
+++ b/mergepdf
@@ -2,17 +2,25 @@
 
 # Merge multiple pdf files into one
 # Requires: gs
+
 # Usage: mergepdf [-o outname] file1.pdf file2.pdf ...
 
 outname=merged.pdf
 
+usage() {
+        echo "Usage: mergepdf [-o OUTFILE] file1.pdf file2.pdf ..."
+}
+
 while getopts "o:" opt; do
         case "$opt" in
                 o)
                         outname="$OPTARG"
                         ;;
+                *)
+                        usage
+                        ;;
         esac
 done
-shift `expr $OPTIND - 1`
+shift $((OPTIND - 1))
 
-gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=$outname $@
+gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile="$outname" "$@"